Disney has announced that the Star Wars: Galactic Starcruiser has sold out of all remaining bookings ahead of its closure at the end of September.
Disney does note that a limited number of additional rooms may become available, likely due to the possibility that some guests might cancel their voyage, however this unlikely to be a widespread occurrence.
Disney released the following statement:
As of May 26, 2023 at 4:30pm ET, Star Wars: Galactic Starcruiser is unavailable for new bookings.
However, availability may still be subject to change and a very limited number of rooms could become available for new bookings from time to time. Please continue to check the online calendar for the latest availability.
Walt Disney World Statement